Firearm and Firearm Shoulder Stock Conversion System

ABSTRACT

A firearm conversion system has a uniquely designed, unitary shoulder stock adapter. The adapter is configured to fixedly attach to a specially provided shoulder stock at one of its ends, and, at its other end, to fixedly attach to the trigger housing assembly and pistol grip of a Smith &amp; Wesson, Model 76 sub-machine gun. When properly installed, the conversion components create a newly designed sub-machine gun having a fixed, comfortable shoulder stock with a longitudinal axis in fore and aft alignment with the longitudinal axis of the adapter and the trigger housing assembly.

FIELD OF THE INVENTION

This invention relates to an improvement in the design of a firearm, specially directed, but not limited, to a Smith & Wesson 9 mm, Model 76 sub-machine gun and clones (S&W 76 sub-machine gun).

BACKGROUND OF THE INVENTION

The design of the S&W 76 sub-machine gun was initially designed and produced for the U.S. Navy in 1967, for the purpose of military operations in Southeast Asia. However, only several thousand of these sub-machine guns were produced, since the Navy subsequently decided this type of weapon was not required.

The S&W 76 sub-machine gun is a blowback, select-fire sub-machine gun, fired from its open bolt. It has a folding steel wire shoulder stock, capable of being folded forward to the left in order to save length and provide a compact unit for purposes of military operations. Details relating to the design and construction of the standard components of the S&W 76 sub-machine gun are included in the Mar. 1, 1969 Edition of The Smith & Wesson 9mm Sub-Machine Gun, Model 76 Manual, the contents of which are incorporated by reference herein. Additional information describing this firearm is found on relevant interne websites, e.g. http://world.guns.ru/smg/usa/smith-wesson-m76-e.htm/.

While this firearm remains popular with collectors, the current use of the S&W 76 sub-machine gun as a firearm for shooters renders the folding capability of its shoulder stock unnecessary. As a practical matter, this originally designed shoulder stock not only requires adjustment before the firearm can be used, but also is somewhat uncomfortable and unstable when being fired. Also, the foldable aspect of the shoulder stock requires additional, unnecessary moving parts, which makes it more susceptible to breakage and repair.

SUMMARY OF THE INVENTION

It is thus the object of the present invention to overcome the limitations and disadvantages inherent in the standard S&W 76 sub-machine gun.

It is an object of the present invention to modify the S&W 76 sub-machine gun to create a newly designed weapon having a fixed, comfortable shoulder stock.

It is another object of the present invention to modify the S&W 76 sub-machine gun such that the sighting of the firearm allows the shooter to assume a more natural firing position.

It is still another object of the present invention to provide a firearm shoulder stock conversion system which alters an existing S&W 76 sub-machine gun such that it has a fixed, comfortable shoulder stock.

It is a further object of the present invention, to provide a uniquely designed shoulder stock/adapter, configured to be utilized with standard components of an S&W 76 sub-machine gun without modification of the gun.

It is another object of the present invention to provide a firearm shoulder stock conversion system which can be utilized, along with the standard components of an S&W 76 sub-machine gun, to easily and conveniently interchange the standard, folding shoulder stock and the fixedly mounted shoulder stock of the invention.

These and other objects are accomplished by a firearm conversion system having a uniquely designed, unitary shoulder stock adapter. The adapter is configured to fixedly attach to a specially provided shoulder stock at one of its ends, and, at its other end, to fixedly attach to the trigger housing assembly and pistol grip of a Smith & Wesson, Model 76 sub-machine gun. When properly installed, the conversion components create a newly designed sub-machine gun having a fixed, comfortable shoulder stock with a longitudinal axis in fore and aft alignment with the longitudinal axis of the adapter and the trigger housing assembly.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention, itself, however, both as to its design, construction and use, together with additional features and advantages thereof, are best understood upon review of the following detailed description with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of the shoulder stock adapter of the present invention.

FIG. 2 is a rear perspective view of the shoulder stock adapter of the present invention.

FIG. 3 is an exploded view of the components of the firearm shoulder stock conversion system, illustrating the manner of attachment to the trigger housing assembly and pistol grip of an S&W 76 sub-machine gun.

FIG. 4 is a view similar to FIG. 3, illustrating the next step in the attachment of the firearm shoulder stock conversion system of the present invention to the trigger housing assembly and pistol grip of an S&W 76 sub-machine gun.

FIG. 5 is an elevation view showing an S&W 76 sub-machine gun fully assembled with the firearm shoulder stock conversion system of the present invention.

DESCRIPTION OF THE INVENTION

Sub-machine gun shoulder stock adapter 1 is an integral, unitary component having main body 2 with longitudinal axis 4. Adapter 1 has aft end 6 comprising cavity S with connection means, namely internal threads 10 or their equivalent, and stock receiving slot 12. Forward end 14 of adapter 1 has adapter channel 16 bordered by channel walls 18 and 20. Attachment bar 22 extends downwardly, perpendicular to main body 2. Through opening 24 and threaded opening 26 are also located at forward end 14.

Pistol grip 30 comprises a hollow handle grip section 32 and top section 34 with elongated top channel 36 and opening 38.

Shoulder stock 40 has longitudinal axis 42 and, at its forward end 44, connector element 46 having external threads 48. Stock tab 50 extends from forward end 44 of shoulder stock 40 as well.

Trigger housing assembly 52, mounted below receiver assembly 54, has longitudinal axis 56. Trigger housing assembly 52 comprises end mounted bracket extension 58 with threaded opening 60.

Pistol grip 30, trigger housing assembly 52, and receiver assembly 54 are all standard components of the Smith & Wesson Model 76 sub-machine gun and like firearms.

In order to convert the standard Smith & Wesson 76 sub-machine gun in accordance with the present invention, the existing folding shoulder stock assembly of the firearm, connected by a grip assembly screw, both components provided as standard on the firearm, is first removed, thereby disconnecting pistol grip 30.

Replacement shoulder stock 40 is attached to adapter 1 by threaded engagement between connector element 46 and threaded opening 26 of the adapter, with stock tab 50 being inserted into stock receiving slot 12. Channel 16 of adapter 1 is slid over bracket extension 58 of trigger housing assembly 52. A first attachment means, presented as adapter attachment bolt 62, is inserted through opening 24 of adapter 1, and is then threadably engaged within threaded opening 60 of bracket extension 58 to secure adapter 1 to trigger housing assembly 52 and generally to firearm 100.

Finally, attachment bar 22 is inserted into top channel 36 of pistol grip 30. A second attachment means, presented as grip attachment bolt 64, is then positioned through hollow handle grip section 32, through opening 38, and inserted into and threadably engaged with threaded opening 26 in adapter 1, to attach pistol grip 30 to the adapter.

Fixedly rigid attachment of shoulder stock 40, adapter 1, and trigger housing assembly 52 of firearm 100 is then complete, such that the longitudinal axii of each of these components, 4, 42, and 56, are in fore and aft alignment. See FIG. 5. Firearm 100 is then ready for use.

While the above description is particularly centered on the shoulder stock connection of a Smith & Wesson Model 76 sub-machine gun, minimal changes to adapter 1 can be made to convert firearms similar to the Smith & Wesson 76 sub-machine gun and, as such, the descriptions herein are not to be considered so restrictive.

Certain novel features and components of this invention are disclosed in detail in order to make the invention clear in at least one form thereof. However, it is to be clearly understood that the invention as disclosed is not necessarily limited to the exact form and details as disclosed, since it is apparent that various modifications and changes may be made without departing from the spirit of the invention. 

1-10. (canceled)
 11. A shoulder stock adapter for a firearm comprising a shoulder stock having a longitudinal axis, a connector element, and a stock tab, a trigger housing assembly with a longitudinal axis and an end mounted bracket extension, and a pistol grip having a handle grip section and a top section with an elongated top channel, said adapter being a single component independent of the shoulder stock and comprising: a singular, integral, unitary main body with a longitudinal axis, said main body with an aft end and a forward end, said aft end of the main body having a cavity comprising connection means for engaging the connector element and fixedly attaching the shoulder stock to the adapter, said forward end of the adapter comprising an adapter channel inset within the main body of the adapter to be slidably mounted over the bracket extension, a stock slot for receiving the stock tab, and an attachment bar extending perpendicular from the main body, said bar located within the top channel of the pistol grip; whereby upon installation of the adapter onto the firearm, adapter is located between the shoulder stock and trigger housing assembly, such that the shoulder stock is fixedly secured to the adapter and the adapter is fixedly secured to the trigger housing assembly, the longitudinal axii of the shoulder stock, adapter, and assembly being in fore and aft alignment.
 12. The shoulder stock adapter as in claim 11 wherein the adapter further comprises a threaded opening for attaching the adapter to the pistol grip.
 13. The shoulder stock adapter as in claim 12 wherein the adapter further comprises a second opening for attaching the adapter to the trigger housing assembly. 